Although a completely separate island that needs to be reached by way of ferry, Governors Island is technically part of the borough of Manhattan. To reach the destination -- which is open from late May through the end of September and is less than a half mile away from Lower Manhattan -- you can take a free ferry from the Battery Maritime Building at 10 South Street. Originally a military outpost, Governors Island began allowing warm-weather visitors in 2006. The island features 172 acres of history and tranquility through heritage sites, biking, picnicking, art and culture. Two remaining 19th-century forts, Fort Jay and Castle Williams, take visitors back to when the island was used for inner harbor defense. Additionally, because there are no cars or motorized vehicles allowed on the island, visitors enjoy renting bikes and cycling along the island’s 2.2-mile Great Promenade or to Picnic Point for some lunch and a direct view of the Statue of Liberty. There are also many art and culture attractions and events on the island, like outdoor art installations, music concerts and the Governors Island annual Governors Island Art Fair which showcases works from over 100 artists.